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MKROCOfV MfOUITION TBT OMIT 
 
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Circnkr D. jb C. S. 
 14 
 
 CAUSES OF VARIATION IN THE PERCENTAGE OF 
 FAT IN HAND SEPARATOR CREAM 
 
 DePARTMK.NT of AoBIfULTlRE, 
 
 Office or the Dairy and Cold Storaoe Commissioner, 
 
 Ottawa, Aii»nist Itt. 1915. 
 Patrons of cream gathering creameries fmi»c-ntly t-unipluin of the variation. 
 7i™t°"""f V^^ percentage of fat a. revc-alo.! by the te«t of the cream dXeZ 
 ^leZt iT I'^'^ -"-ti"- have given ri«e to more or less dissatis cUol 
 
 thl -n"^ 1 ^ °"^ """^ ''"y" '''"' '^' ^"''•^ "^ unnecessary friction between 
 
 them and the managers of creameries. "vi«ccu 
 
 at the Finch Dairy S ation and the results are published herein with a view of explain- 
 S^tlrs ''""'""" '""'^ ^ "^"^ *" irregularities in the running of ilZel 
 
 In nearly all separators the proportion of cream is regulated by what is termed 
 . "cream screw." When this sc-ew or plug is turned to3s the centTe of the™^ 
 It contracto the cream line and gives a richer or higher testing cream. Turning it 
 outwards widens the cream line and, therefore, allows a larger proportion of the skim- 
 milk to pass out with the fat and thus gives a thinner or lower testing cream 
 
 Considering the question of separation from a purely mechanical standpo"int one 
 would naturally come to the conclusion that once the cream screw is set at any desired 
 point the separator would always deliver cream containing the same percentageTf 
 fat. We must, however, consider several other factors which very materially affert th« 
 working of a cream separator. The following are the most important onesi- 
 
 (1) The Percentage of Fat in the IfiZfc.-Milk from a single herd will vary in fat 
 content from day to day, sometimes to quite an extent. This variation will affect th« 
 per cent fat in thecream. For instance, in milk testing 4 per cent, there are four 
 pounds of fat in 100 pounds of milk; in milk testing 3 per cent fat there IZ oZ 
 three pounds of fat in 100 pounds of milk. If 100 pounds of each lot of milk^s run 
 through a separator under exactly the same conditions as to time speed temDerat.,™ 
 etc.. there ^ill be practically the same number of pounds of cream', but there would ^ 
 practically one pound of fat more in the cream frem the 4 per cent milk, which would 
 give a correspondingly higher testing cream than would be taken from the 3 per cent 
 
 (2) Temperature of the Millc.-m\k at 70 degrees temperature is thicker or mor« 
 viscous than the same milk would be if heated to 95 degrees; it will therefore not 
 run through the separator as fast, the cream line will be narrower and the cream will 
 test higher from milk at 70 degrees than from the same lot of milk separated at 95 
 
 (3) Flow of Milk into Separator.— The milk inlet on all separators is made to 
 feed the separator to its full capacity. If the flow of milk is partly shut off, the cream 
 line will be narrower and a richer or higher testing cream will bo the result 
 
 84468—1 
 
 ; 
 
 f 
 
 I 
 
i<m 
 
 flLlr^ ''^ t'.**" -ep-ritor. If the .peed is inof«Md. the oentrifug.! preMui i. 
 
 #.* J"!i!**^" '^'j*'"* "*"** ^"^ •'~''' condition, would affect the percenUw of 
 
 «!n»- -Iir*!!5A ? •*^"" *""" '™""** '••*• "" »''• '"Wect, the following exwri- 
 menu were carried out, uaing & 400-pound hand Mparator. 
 
 .11 Jk *'"'A." ''I"? the reault. of .eparatiug the milk at different temperature^ 
 ril other condition, be.ng the s»me. One run was made from the wme milk "t elS 
 temperature .Utod on three different day.. The figure, given are the aver^ of the 
 ti^ dayfc Mixed night', and morning', milk from the .ame patron, wa.^ each 
 
 Tablb I.— Separating at Different Temperature.. 
 
 Per Crat Fst 
 in Milk. 
 
 Temp, of Milk »t 
 SflparatinK. 
 
 Lba. Crpatn per 100 
 lb.. .Milk. 
 
 Per Cent F*t in 
 Cnxni. 
 
 Per Cent Fat in 
 
 Skim-milk. 
 
 II 
 
 367 
 
 70d«gnM 
 78 H 
 80 H 
 8ft „ 
 
 as „ 
 
 LU. Os. 
 
 ■ 
 S 14 
 
 10 
 
 10 n 
 
 11 a 
 13 a 
 
 44 3 
 400 
 SSS 
 
 83 1 
 330 
 29-3 
 
 'MO 
 0S3 
 
 on 
 
 038 
 •017 
 .031 
 
 Here we find a variation of 14-9 per cent fat in the test .f the cream with all the 
 condition, the .ame. eicept the temperature of the milk. The pounds of cream per 
 one hundred pound, of milk increaw. a. the temperature of the milk is raisrd nnd it 
 must also be noted that the percentage of fat in the skim-milk increases as the tem- 
 perature of the milk is lowered. 
 
 Table H .how. the effect of changing the speed of the seperator. The figures 
 given are the average of three run. at each speed on thre^, different days. 
 
 Table II.— Variation in the Speed of tl' Feperator. 
 
 Per Cent Fat 
 in Milk. 
 
 S'63 
 8 63 
 3-63 
 S'6S 
 
 Tempentturn 
 of Milk. 
 
 SSdeg. 
 
 95 n 
 
 96 .. 
 96 » 
 
 Speed tnmed 
 per minute. 
 
 88 
 
 •60 
 66 
 60 
 
 Lbi. Cream 
 100 Lbs. Mi 
 
 nt Fat 
 eim. 
 
 Lbt. Oa. 
 
 9 
 13 
 15 
 18 
 
 14 
 
 7 
 
 14 
 
 866 
 301 
 3S4 
 
 19-3 
 
 •Correct apeed. 
 
 Per Cent Fat 
 in Skim-milk. 
 
 ■018 
 •017 
 •033 
 •037 
 
 - A metronome wa. used xo count the turns of the handle, so that the speed of the 
 separator was absolutely the same during the whole run. It was found extremelv 
 difficult to turn the separator at a uniform ^peed throughout an entire run, and unless 
 the oiierator has a reliable indicator, there is likely to be a considerable variation in 
 the speed of the separator. The writer is of the opinion that the speed of the seperator 
 has probably more to do with the variations in the cream tests than any other con- 
 dition. 
 
FlT« turn, pn ninoto nndw pr .^.^ .prad nuufe ••T p»r rant diSmno* in the 
 Ui^, and ten turns too slow made a difftrenee of 100 per c*nt. The difference in the 
 twt between flTe turns too fast and ten turns too slow was 17-4 per cent, the per- 
 centage heinc only a little oTer half in one case what it was in the othe.-. 
 
 Turning the seperator too slow also causes a greater loss of fat in the skim-milk. 
 Ten rerolut'ons per miuuto too slow increased the loss of fat 0-1 per cent 
 
 Tabu III.-6howing the effect of Low Speed and Low Temperature Combined on the 
 Percentage of Fat m the Cream and Loss of Fat in the Skim-milk. Throe Runs 
 were made from the same Milk on Three different Days. 
 
 * 1 ■_ 
 
 Pa Cent Fat 
 
 in Milk. 
 
 SpMdtnnMK) 
 psrniiaut*. 
 
 Twniwflktura 
 oi Milk. 
 
 Per Cent Fat 
 in CrMin. 
 
 Per C«^t Fat 
 in 8kibi.milk. 
 
 sa 
 a-6 
 s-a 
 
 50 
 M 
 60 
 
 70 dcifrraas. 
 80 „ 
 M 
 
 S8S 
 
 270 
 21 8 
 
 •078 
 -003 
 OJO 
 
 There is not as great a variation in the percentage fat in the cream as in some 
 of the other tables, but the loss of fat in the skim-milk is very high at tho low tem- 
 peratures, showing that the best results will be obtained by turning the seperat r at 
 it8 proper speed and having the milk at a temperature of 96 or 96 degrees 
 
 Two run* were made from milk testing 3-3 per cent and two from milk testing 
 4-5 per cent. Tlie following table shows the average results:— 
 
 Table IV.-Variation in the per cent Fat in the Cream from Milk containing 
 different percentages of Fat. 
 
 Speed of Soparatur. 
 
 M 
 
 Temp, of Milk. 
 
 M-5 
 
 8B-e 
 
 Per cent F»t in Milk. 
 
 SS 
 4-6 
 
 Per cent Fat in 
 Cream. 
 
 370 
 3S-5 
 
 PtT cfnt Fat in 
 Skim-milk. 
 
 •017 
 ■015 
 
 Here we find a difference of 1-2 per cent of fat in the milk made a difference of 
 86 per cent in the cream test. There will not be so much variation as 1-2 per cent 
 fat in the milk from the same herd from day to day. but there may be a difference 
 0-6 per cent, which at the same rate of variation would equal 3-6 per cent in the test 
 of the cream. 
 
 The foregoing results show very plainly that different conditions in the milk and 
 only slight changes m the operating of the separator, without changing the cream 
 screw, will make wide variations in the percentage of fat in the cream. If the tem 
 perature of the milk is too low, or the speed of the separator is reduced below the 
 required number of revolutions per minute, the variations will be accompanied bv an 
 excessive loss of fat in the skim-milk. 
 
 A good separator, properly handled, will deliver cream testing anywhere from 20 
 to 36 per cent fat and not leave over 002 per cent fat in the skim-milk. 
 
 To give the best resulte in butter-making cream should test 30 to 36 per cent fat. 
 
 GEO. H. BARR, 
 
 Ohief, Dairy Diviiion, 
 
 ; i 
 
 ■il